题目：
树的子结构
题目描述：
输入两棵二叉树A，B，判断B是不是A的子结构。（ps：我们约定空树不是任意一个树的子结构）
解题：
/*
struct TreeNode {
int val;
struct TreeNode *left;
struct TreeNode *right;
TreeNode(int x) :
val(x), left(NULL), right(NULL) {
}
};*/
class Solution {
bool isSubtree(TreeNode* pRootA, TreeNode* pRootB) {
if (pRootB == NULL) return true;
if (pRootA == NULL) return false;
if (pRootB->val == pRootA->val) {
return isSubtree(pRootA->left, pRootB->left)
&& isSubtree(pRootA->right, pRootB->right);
} else return false;
}
public:
bool HasSubtree(TreeNode* pRootA, TreeNode* pRootB)
{
if (pRootA == NULL || pRootB == NULL) return false;
return isSubtree(pRootA, pRootB) ||
HasSubtree(pRootA->left, pRootB) ||
HasSubtree(pRootA->right, pRootB);
}
};
